Integral negative/positive color diffusion transfer process film unit employing in situ generated visible light-reflecting agent

ABSTRACT

This application is directed, in general, to an integral negative/positive color diffusion transfer process film unit which comprises a dimensionally stable common support carrying on one surface a dyeable polymeric layer, a photosensitive silver halide emulsion layer having associated dye transfer imageforming material and a layer comprising a light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent intermediate the dyeable polymeric layer and the photosensitive silver halide emulsion layer, and to specified diffusion transfer color processes employing such a film unit.

United States Patent Land [451 Mar. 7, 1972 INTEGRAL NEGATIVE/POSITIVE COLOR DIFFUSION TRANSFER PROCESS FILM UNIT EMPLOYING IN SITU GENERATED VISIBLE LIGHT- REFLECTING AGENT Inventor: Edwin H. Land, Cambridge, Mass.

Assignee: Polaroid Corporation, Cambridge, Mass.

Filed: June 5, 1970 Appl. No.: 43,741

US. Cl ..96/3, 96/29 D, 96/84 R,

' 96/76 C Int. Cl ..G03c 7/00, G03c 5/54, G030 1/84 Field of Search ..96/3, 29 D, 84 R, 77

References Cited UNITED STATES PATENTS Land ..96/3

Primary Examiner-Norman G. Torchin Assistant ExaminerAlfonso T. Suro Pico Attorney-Brown and Mikulka and Robert M. Ford ABSTRACT layer, and to specified diffusion transfer color processes employing such a film unit.

43 Claims, 16 Drawing Figures LAYER LAYER tnuulofl urea SILVER HALIDE EUULSN LAYER DEVELOPER LAYER SILVER RAIJDE EMULSION LAYER DEVELOPER LAYER SUPPORT LAYER PATENTEDMAR' 7 m2 SHEET 2' BF 8 INVENTOR. EDWIN H. LAND BY 25W. W1 mm a/rwl M 722. 7 ATTORNEYS PATENTEUMAR 7 I972 SHEET 1 0F 8 mm i 8 INVENTOR. EDWIN H. LAND @lumm and M and [30W 772. gm

AT TORN E YS PATENIEUMAR 7 I972 SHEET 5 OF 8 EEWEEE 5:] 5.3.53 E6 od? 553 206 55 "3341 53m wzcmzuw 5 5 mu 0. i mN om uufimnw @225.

INVENTOR. EDWIN H. LAND ATTORNEYS INTEGRAL NEGATIVE/POSITIVE COLOR DIFFUSION TRANSFER PROCESS FILM UNIT EMPLOYING IN SITU GENERATED VISIBLE LIGHT-REFLECTING AGENT photographic products particularly adapted for employment W in diffusion transfer color processes; to provide photographic products which comprise a photosensitive laminate which contains a plurality of layers including a dimensionally stable common support carrying on one surface a dyeable polymeric layer and a photosensitive silver halide emulsion layer having a dye image-forming material which is processing composition diffusible, as a function of the point-to-point degree of the emulsions exposure to actinic radiation, and a layer permeable to processing composition solubilized dye image-forming material comprising visible light-reflecting agent precursor in a concentration sufficient to mask dye image-forming material associated with the photosensitive silver halide emulsion layer subsequent to and as a function of processing, positioned intermediate the dyeable polymeric layer and the photosensitive silver halide emulsion layer and associated dye image-forming material; to provide photographic diffusion transfer products comprising a film unit including a photosensitive laminate, of the last-identified type, in combination with a rupturable container retaining a processing composition; to provide a diffusion transfer photographic film unit, of the last-identified type, wherein the container is fixedly positioned and extends transverse a leading edge of the photosensitive laminate whereby to effect, upon application of compressive pressure, discharge of the processing composition contiguous the surface of the laminate opposite the dimensionally stable support layer; to provide a diffusion transfer film unit, of the last-identified type, including a dimensionally stable sheet superposed substantially coextensive the surface of the laminate opposite the dimensionally stable support and the rupturable container fixedly positioned and extending transverse a leading edge of the photosensitive laminate and adapted to effect, upon application of compressive pressure, unidirectional discharge of the containers contents intermediate the sheet and the laminate; to provide a diffusion transfer film unit, of the last-identified type, wherein the separate dimensionally stable sheet possesses a leading edge fixedly positioned extending transverse a leading edge of the laminate and is adapted to be superposed subsequent to photoexposure of the laminate substantially coextensive the surface of the laminate opposite the dimensionally stable common support and the rupturable container retaining the processing composition is adapted to effect, upon application of compressive pressure, unidirectional distribution of the containers processing composition intermediate the sheet and the laminate upon superpositioning of the sheet coextensive the surface of the laminate; and to provide photographic diffusion transfer color processes employing such products.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the product possessing the features, properties and the relation of components and the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGS. I, 2 and 3 are diagrammatic enlarged cross-sectional views of one embodiment of the photographic film unit of the present invention illustrating the association of elements during the three illustrated stages of the performance of a difiusion transfer process, for the production of a multicolor transfer image according to the invention, the thickness of the various materials being exaggerated, and wherein FIG. 1, represents an exposure stage, FIG. 2 represents a processing stage and FIG. 3 represents a product of the process;

FIG. 4 is a perspective view of a second embodiment of the photographic film unit of the present invention;

FIGS. 5, 7 and 9 are diagrammatic enlarged cross-sectional views of a first film unit of FIG. 4, along section line AA, illustrating the association of elements during the three illustrated stages of the performance of a multicolor diffusion transfer process according to the invention, the thickness of the various materials being exaggerated, and wherein FIG. 5 represents an exposure stage, FIG. 7 represents a processing stage and FIG. 9 represents a product of the process;

FIGS. 6, 8 and 10 are diagrammatic, further enlarged crosssectional views of the film unit of FIGS. 5, 7 and 9; along section lines 6-6, 88 and I0l0, respectively, further illustrating, in detail, the arrangement of layers comprising the photosensitive composite structure during the three illustrated stages of the transfer process;

FIGS. ll, 13 and 15 are diagrammatic enlarged cross-sectional views of a second film unit of FIG. 4, along section line A-A, illustrating the association of elements during the three illustrated stages of the performance of a multicolor diffusion transfer process according to the invention, and wherein FIG. 11 represents an exposure stage, FIG. I3 represents a processing stage and FIG. 15 represents a product of the process; and

FIGS. 12, 14 and 16 are diagrammatic, further enlarged cross-sectional views of the film unit of FIGS. 11, I3 and 15 along section lines 12-12, l4I4 and 16-16, respectively, further illustrating, in detail, the arrangement of layers comprising the photosensitive composite structure during the three illustrated stages of the transfer process.

As disclosed in US. Pat. No. 2,983,606, issued May 9, 1961, a photosensitive element containing a dye developer, that is, a dye which is a silver halide developing agent, and a silver halide emulsion may be exposed and wetted by a liquid processing composition, for example, by immersion, coating, spraying, flowing, etc., in the dark, and the exposed photosensitive element superposed prior to, during, or after wetting, on a sheetlike support element which may be utilized as an image-receiving element. In a preferred embodiment, the liquid processing composition is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed relationship with the image-receiving layer. The liquid processing composition, positioned intermediate the photosensitive element and the image-receiving layer, permeates the emulsion to initiate development of the latent image contained therein. The dye developer is immobilized or precipitated in exposed areas as a consequence of the development of the latent image. This immobilization is apparently, at least in part, due to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted and diffusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the point-to-point degree of exposure of the silver halide emulsion. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed imagereceiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image. The imagereceiving element may contain agents adapted to mordant or otherwise fix the diffused, unoxidized dye developer. If the color of the transferred dye developer is affected by changes in the pH of the image-receiving element, this pH may be adjusted in accordance with well-known techniques to provide a pH affording the desired color. The desired positive image is revealed by stripping the image-receiving layer from the photosensitive element at the end of a suitable imbibition period.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By.a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and orthoand para-amino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

Multicolor images may be obtained using color image-fon'ning components such as, for example, the previously mentioned dye developers, in diffusion transfer processes by several techniques. One such technique contemplates obtaining multicolor transfer images utilizing dye developers by employment of an integral multilayer photosensitive element, such as is disclosed in the aforementioned U.S. Pat. No. 2,983,606, and particularly with reference to FIG. 9 of the patents drawing, wherein at least two selectively sensitized photosensitive strata, superposed on a single support, are processed, simultaneously and without separation, with a sin gle, common image-receiving layer. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in thesilver halide emulsion layer, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide emulsion strata. Each set of silver halide emulsion and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

The dye developers are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, that is, the previously mentioned cyan, magenta and yellow. The dye developers employed may be incorporated in the respective silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide emulsion. Specifically, the dye developer may, for example, be in a coating or layer behind the respective silver halide emulsion and such a layer of dye developer may be applied by use of a coating solution containing about 0.5 to 8 percent, by weight, of the respective dye developer distributed in a film-forming natural, or synthetic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the chosen diffusion transfer fluid processing composition.

As examples of materials, for use as the image-receiving layer, mention may be made of solution dyeable polymers such as nylon as, for example, N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate with filler as, for example, one-half cellulose acetate and one-half oleic acid; gelatin; and other materials of a similar nature. Preferred materials comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, as disclosed in U.S. Pat. No. 3,148,06l, issued Sept. 8, 1964.

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of I00 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

In accordance with aforementioned U.S. Pat. No. 2,983,606, an image-receiving layer of the type disclosed in that patent need not be separated from its superposed contact with the photosensitive element, subsequent to transfer image formation, if the image-receiving element is transparent and a processing composition containing a substance rendering the processing composition layer opaque is spread between the image-receiving layer and the silver halide emulsion or emulsions.

However, it has been found, if the image-receiving element is maintained in contact with the photosensitive element, subsequent to dye developer transfer image formation, and includes the presence of an alkaline processing composition,

necessarily having a pH at which dye developer, for example,

in reduced form, diffuses to form the dye transfer image, intermediate the elements, the transfer image thus formed is unstable over an extended period of time. The dye image instability is due, at least in part to the presence of what is, in general, a relatively high pH alkaline composition in intimate contact with the dye or dyes forming the image. This contact itself provides instability to the molecular structure of dye by, for example, catalyzing degradation and undesirable structural shifts effecting the spectral absorption characteristics of the image dye. In addition, the presence of an alkaline composition, possessing a pH at which the dye, for example, in reduced form, diffuses, also provides an integral dynamic system wherein oxidized dye, immobilized in areas of the photosensitive element, as a function of its development, with the passage of time attempts to generate, in such areas, an equilibrium between oxidized and reduced dye. In that the pH of the dynamic system is such that diffusion of the reduced form of the dye will occur, such reduced dye will, at least in part, transfer to the image-receiving layer and the resultant diffusion will imbalance the equilibrium, in such areas of the photosensitive element, in favor of additional formation of reduced dye. As a function of the efficiency of the imagereceiving layer, as a dye sink, such nonimagewise dyeing of the image-carrying layer still further imbalances the equilibrium in favor of the additional formation of dye in reduced, diffusible form. Under such circumstances, the transfer image definition, originally carried by the image-receiving layer, will suffer a continuous decrease in the delta between the images maximum and minimum densities and may, ultimately, result in the image-receiving elements loss of all semblance of image definition; merely becoming a polymeric stratum carrying a relatively uniform overall dyeing.

Any attempt to decrease the dye sink capacity of the imagecarrying layer, for example, by reduction of its mordant capacity, in order to alleviate, at least to an extent, the action of the image-receiving layer as a dye sink, however, will enhance diffusion of the dye, comprising the transfer image, from the image-carrying layer, to the remainder of the element due, at least in part, to the continued presence of the alkaline composition having a pH at which the reduced form of the dye, forming the transfer image, is diffusible. The ultimate result is substantially the same overall image distortion as occurs when the image-receiving layer acts as a dye sink, with the exception that the dye is more extensively distributed throughout the film unit and the ultimate overall dyeing of the image-receiving layer itself is of lower saturation.

The problems inherent in fabricating a film unit of the type wherein the image-receiving element, the alkaline processing composition and the photosensitive element are maintained in contiguous contact subsequent to dye transfer image formation, for example, a film unit of the type described hereinbefore with reference to aforementioned U.S. Pat. No. 2,983 ,606, may be effectively obviated by fabrication of a film unit in accordance with the physical parameters specifically set forth in U.S. Pat. Nos. 3,415,644; 3,415,645; and 3,415,646, issued Dec. 10, 1969, respectively, in the name of Edwin H. Land.

Specifically an integral photographic film unit particularly adapted for the production of a dye transfer image of unexpectedly improved stability and other properties, by a color diffusion transfer process will be constructed, for example, in accordance with aforementioned U.S. Pat. No. 3,415,644, to include a photosensitive element comprising a laminate having, in sequence, as essential layers, a dimensionally stable opaque layer; a photosensitive silver halide emulsion layer having associated therewith dye image-providing material which is soluble and diffusible, in alkali, at a first pH; an alkaline solution permeable polymeric layer dyeable by the dye image-providing material; a polymeric acid layer containing sufficient acidifying groups to effect reduction, subsequent to substantial transfer dye image formation, of a selected processing solution having the first pH to a second pH at which said dye image-providing material is insoluble and nondiffusible; and a dimensionally stable transparent layer. In combination with the laminate, a rupturable container retaining an aqueous alkaline processing composition having the first pH and containing an opacifying agent, in a quantity sufficient to mask the dye image-providing material, is fixedly positioned and extends transverse a leading edge of the laminate whereby to effect unidirectional discharge of the containers contents between the alkaline solution permeable and dyeable polymeric layer and the photosensitive silver halide emulsion layer next adjacent thereto, upon application of compressive force to the container.

It will also be recognized that the dimensionally stable polymeric support layer next adjacent the photosensitive silver halide emulsion layer or layers may be transparent, as disclosed in aforementioned U.S. Pat. No. 3,415,646, and that in such instance the opacifying agent may be initially dispersed in the composite film unit intermediate the dyeable polymeric layer and the silver halide emulsion layer next adjacent, as disclosed in aforementioned U.S. Pat. No. 3,415,645.

Employment of the last-mentioned film units, according to the described color diffusion transfer photographic process, specifically provides for the production of a highly stable color transfer image accomplished, at least in part, by effectively obviating the previously discussed disadvantages of the prior art products and processes, by in process adjustment of the environmental pH of the film unit from a pH at which transfer processing is operative to a pH at which dye transfer is inoperative subsequent to substantial transfer image formation. The stable color transfer image is obtained irrespective of the fact that the film unit is maintained as an integral laminate unit during exposure, processing, viewing, and storage of the unit, which transfer image exhibits the required maximum and minimum dye transfer image densities, dye saturation, hues and definition.

Film units fabricated in accordance with the parameters set forth above specifically disclose the presence of the stated polymeric acid component to effect in situ process adjustment of the film units operational pH range.

Specifically, the film units require the presence of a polymeric acid layer such as, for example, of the type set forth in U.S. Pat. No. 3,362,819 which, most preferably, includes the presence of an inert timing or spacer layer intermediate the acid containing layer carried on a support and the imagereceiving layer.

As set forth in the last-mentioned patent, the polymeric acid layer comprises polymers which contains acid materials, such as integral carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium, etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, restrained from the acid polymer layer. In the preferred embodiments disclosed, the acid polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming watersoluble sodium and/or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid halfester derivatives of cellulose which derivatives contain frec carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., 0-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether/maleic anhydride copolymers; etc.

As previously noted, the pH of the processing composition preferably is of the order of at least 12 to 14. The acid polymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image layer from a pH of about 12 to 14 to a pH of at least 1 l or lower at the end of the imbibition period, and preferably to a pH of about 5 to 8 within a short time after imbibition, thus requiring, of course, that the action of the neutralizing acid be accurately so controlled as not to interfere with either development of the negative or image transfer of unoxidized dye developers. For this reason, the pH of the image layer must be kept at a functional transfer level, for example, 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to a pH below that at which dye transfer may be accomplished, for example, at least about 11 and preferably about pH 9 to 10. Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of, for example, 12 to 14 until transfer of the necessary quantity of dye has been accomplished. The subsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in positive image density, the acid groups are disclosed to be so distributed in the acid polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid material in the acid polymer layer may be effected by mixing an acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only the acid polymer but selecting one having a relatively lower proportion of acid groups, These embodiments are illustrated, respectively, in the cited copending application, by (a)'a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mew tioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acid may contain a water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed. As examples of cellulose esters contemplated for use, mention is made of cellulose acetate, cellulose acetate butyrate, etc. The particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength and when necessary or desirable, suitable subcoats are employed to help the various polymeric-layers adhere to each other during storage and use.

In US, Pat. No. 3,362,821, it is also disclosed that the acid polymeric layer may be disposed within the photosensitive element of the film unit intermediate that elements support and next adjacent photosensitive silver halide emulsion layer and associated dye image-providing material, with the optional presence of a spacer or timing layer intermediate the acid layer and next adjacent silver halide emulsion layer.

The inert spacer layer of the last-mentioned patent, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin, acts to time control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It is there stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer.

It has now been quite unexpectedly discovered that the problems inherent in fabricating a film unit of the type where the image-receiving element and the photosensitive element are maintained in contiguous contact during processing and subsequent to dye transfer image formation, for example, a film unit of the type described, with reference to aforementioned US. Pat. No. 2,983,606, may be effectively obviated in a considerably simplified manner by fabrication of a film unit in accordance with the physical parameters detailed below.

Specifically, it has been quite unexpectedly discovered that an integral photographic film unit of simplified construction and particularly adapted for the production of dye transfer images of desirable properties by a color diffusion transfer process will be constructed to include a photosensitive element comprising a laminate structure possessing, as essential layers: a dimensionally stable common support carrying on one surface a photosensitive silver halide emulsion layer having associated therewith a dye image-forming material which is soluble and diffusible in processing composition as a function of the point-to-point degree of exposure of the photosensitive silver halide emulsion layer to incident actinic radiation; a layer permeable to processing composition diffusible dye image-forming material which comprises a reflecting agent precursor present in a concentration sufficient to mask dye image-forming material associated with the photosensitive silver halide emulsion layer subsequent to and as a function of processing; and a polymeric layer dyeable by the dye imageforming material.

In a preferred embodiment of the present invention the dimensionally stable common support is opaque and the photosensitive silver halide emulsion layer is positioned intermediate the support and the dyeable polymeric layer and the transfer image is viewed at the surface of the laminate opposite the opaque support subsequent to processing of the film unit. In a second embodiment of the invention the dimensionally stable common support is transparent and the dyeable polymeric layer is positioned intermediate the support and the photosenstive silver halide emulsion layer, where it is intended that the dye transfer image be viewed through the support and/or the image residing in the photosensitive silver halide emulsion layer be viewed at the surface of the laminate opposite the support, subsequent to processing, or the photosensitive silver halide emulsion layer is positioned intermediate the support and the dyeable polymeric layer, where it is intended that the dye transfer image be viewed at the surface of the laminate and/or the image residing in the photosensitive silver halide emulsion layer, subsequent to processing, be viewed through the support.

In the preferred embodiments of the present invention, the film unit is specifically adapted to provide for the production of a multicolor dye transfer image and the photosensitive laminate comprises, as essential layers, at least two selectively sensitized silver halide emulsion strata each having dye imageproviding materials of predetermined color associated therewith which are soluble and diffusible in processing composition as a function of the point-to-point degree of exposure of the respective associated silver halide emulsion strata; a polymeric layer permeable by processing composition solubilized dye image-providing materials which contains a reflecting agent precursor in a quantity sufficient to mask the dyeimageproviding materials associated with the sensitized silver halide emulsion strata subsequent to and as a function of processing; a polymeric layer dyeable by the dye image-providing material; and the dimensionally stable common support layer.

In view of the fact that the preferred dye image-providing materials comprise dyes which are silver halide developing agents, as stated above, for purposes of simplicity and clarity, the present invention will be further described hereinafter in terms of such dyes, without limitation of the invention to the illustrative dyes denoted, and, in addition the photographic film unit structure will be detailed hereinafter employing preferred structural embodiments, without limitation of the invention to the preferred structures denoted.

The silver halide emulsions comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye, which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at a first pH possessing, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the emulsion strata, and its associated dye, is separated from the remaining emulsion strata, and their associated dye, by separate processing solution permeable polymeric interlayers.

In such preferred embodiment of the invention, the silver halide emulsion comprises photosensitive silver halide dispersed in gelatin and is about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous processing solution permeable polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the processing solution permeable polymeric interlayers, preferably gelatin, are about 1 to 5 microns in thickness; the processing solution permeable reflecting agent precursor containing layer is about 0.05 to 0.25 micron in thickness; the processing solution permeable and dyeable polymeric layer is transparent and about 0.25 to 0.4 mil in thickness; and the dimensionally stable' support layer is processing solution impermeable and about 2 to 6 mils in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

In the preferred embodiment of the present invention s film unit for the production of a multicolor transfer image, the respective silver halide/dye developer units of the photosensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/redsensitive emulsion unit distal the laminates exposure surface, the yellow dye developer/blue-sensitive emulsion unit proximal the exposure surface and the magenta dye developer/greensensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.

Reference is now made to FIGS. 1 through 16 of the drawings wherein there is illustrated preferred film units of the present invention and wherein like numbers, appearing in the various figures, refer to like components.

As illustrated in the drawings, each of FIGS. I through 3 illustrate diagrammatic cross-sectional views of a preferred film unit of the present invention during the various depicted stages in the performance of a photographic diffusion transfer process as detailed hereinafter.

As illustrated in FIG. 1, the film unit detailed comprises, prior to processing, a photosensitive laminate including, in order, dimensionally stable opaque support layer 10, preferably an actinic radiation-opaque flexible sheet material; cyan dye developer layer ll; red-sensitive silver halide emulsion layer 12; interlayer I3; magenta dye developer layer 14; green-sensitive silver halide emulsion layer I; interlayer I6; yellow dye developer layer 17; blue-sensitive silver halide emulsion layer 18; reflecting agent precursor layer 19; imagereceiving layer 20; and stripping layer 21.

In the performance of a diffusion transfer multicolor process employing the film unit, the unit is exposed to radiation, actinic to photosensitive laminate l3, incident on the laminates exposure surface, as illustrated in FIG. 1.

Subsequent to exposure, as illustrated by FIGS. 2 and 3, the film unit is processed by distribution of processing composition 22 from applicator 23, on the surface of the laminate opposite opaque support layer 10, possessing a pH and solvent concentration at which the cyan, magenta and yellow dye developers are soluble and diffusible as a function of the point-to-point degree of exposure of red-sensitive silver halide emulsion layer 12, green-sensitive silver halide emulsion layer and blue-sensitive silver halide emulsion layer 18, respectively.

Processing solution 22 penneates emulsion layers l2, l5 and 18 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 11, 14 and 17, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developer, as a function of the pointto-point degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to dyeable polymeric layer to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the in situ process generation of reflecting agent in layer 47 which effects masking of yellow, magenta and cyan dye developer remaining associated with blue-sensitive emulsion layer 18, green-sensitive emulsion layer 15 and red-sensitive emulsion layer 12.

Subsequent to substantial multicolor dye transfer image formation, layer 22 of the processing solution optionally may be manually dissociated from the remainder of the film unit, which may be facilitated by stripping layer 21, as described above, to provide the product illustrated in FIG. 3.

As further illustrated in the drawings, FIG. 4 sets forth a perspective view of the therein specified film units of the present invention, designated 30, and each of FIGS. 5 through 16 illustrate the therein detailed diagrammatic cross-sectional views of such film units, along the stated section line A-A, during the various depicted stages in the performance of the photographic diffusion transfer process as detailed hereinafter.

As detailed in FIGS. 5 to 10, inclusive, film unit 30 comprises rupturable container 31, retaining, prior to processing, aqueous processing solution 22, photosensitive laminate 32 including, in order, image-receiving layer 20; reflecting agent precursor layer 19; blue-sensitive silver halide emulsion layer 18; yellow dye developer layer 17; interlayer l6; green-sensitive silver halide emulsion layer 15; magenta dye developer layer 14; interlayer l3; red-sensitive silver halide emulsion layer 12; cyan dye developer layer 11; spacer layer 29; neutralizing layer 28; and dimensionally stable opaque support layer I0; and, superposed coextensive the surface of the laminate opposite opaque support layer 10, dimensionally stable transparent sheet 24; both support layer 10 and sheet 24 preferably comprising processing composition impermeable flexible sheet material.

As detailed in FIGS. 11 to 16, inclusive, photosensitive laminate 33 may also comprise, in order, red-sensitive silver halide emulsion layer 34 containing cyan dye developer; interlayer 35; green-sensitive silver halide emulsion layer 36 containing magenta dye developer; interlayer 37; blue-sensitive silver halide emulsion layer 38 containing yellow dye developer; reflecting agent precursor layer I9; image-receiving layer 20; spacer layer 29; neutralizing layer 28; and dimensionally stable transparent support layer 39; and, superposed coextensive the surface of the laminate opposite transparent support layer 39, dimensionally stable opaque sheet 40; both support layer 39 and sheet 40 preferably comprising processing composition impermeable flexible sheet material.

The composite may be provided with a binding member extending around, for example, the specified edges of composite, maintaining the laminate and sheet element comprising the composite intact except at the interface ,between the elements during distribution of processing composition 22. As illustrated in the figures, the binder member may comprise a pressurersensitive tape 25 securing the sheet and laminate elements together at the composites specified edges. Tape 25 will also act to maintain processing composition 22 intermediate the sheet and photosensitive laminate upon application of compressive pressure to container 31 and distribution of its contents intermediate the stated elements. Under such circumstances, binder tape 25 will act to prevent leakage of processing composition from the film unit during and subsequent to photographic processing.

Rupturable container 31 may be of the type shown and described in any of U.S. Pat. Nos. 2,543,I8l; 2,634,886; 3,653,732; 2,723,051; 3,056,492; 3,056,491; 3,l52,5l5; and the like. In general, such containers will comprise a rectangular blank of fluidand air-impervious sheet material folded longitudinally upon itself to form two walls 41 which are sealed to one another along their longitudinal and end margins to form a cavity in which processing solution 26 is retained. The longitudinal marginal seal 42 is made weaker than the end seals 43 so as to become unsealed in response to the hydraulic pressure generated within the fluid contents 26 of the container by the application of compressive pressure to walls 41 of the container.

As illustrated in FIGS. 5, 7, l1 and I3, container 3] is fixedly positioned and extends transverse a leading edge of the photosensitive laminate whereby to effect unidirectional discharge of the containers contents 26 between the laminate and next adjacent sheet, upon application of compressive force to container 31. Thus, container 31, as illustrated in FIGS. 5 and I1 is fixedly positioned and extends transverse a leading edge of the laminate with its longitudinal marginal seal 42 directed toward the interface between the laminate and halide emulsion layer; and that reflecting agent may be in part generated within the image-receiving and/or next adjacent silver halide emulsion strata of the film unit.

A particularly preferred embodiment of the present invention employs a metathetical reaction between selected precursor salts, the respective exchange of cations or anions of which provide for the simultaneous generation of two separate reflecting agents such as, for example, the metathetical generation of both barium sulfate and zinc sulfide white, inorganic salt pigments by the in situ reaction of substantially colorless barium sulfide and zinc sulfate precursor salts. Such preferred embodiments provide for the in process generation of an increased quantity of reflecting agent per unit volume of precursor salts employed.

A particularly preferred reflecting agent comprises barium sulfate due to its highly effective reflection properties.

In general, in the preferred embodiments, the reflecting agent precursor selected will, as previously denoted, comprise a precursor specifically adapted to provide a substantially white inorganic pigment which reflects visible light and, in particularly preferred embodiments, will be coated at a coverage effective to provide 200 to 1,000 mgs./ft. reflecting agent, as a result of processing, which coverage is generally sufficient, subsequent to processing, to mask opacifying agent distributed in the processing composition and any residual dye developer present intermediate the image-receiving layer and the dimensionally stable opaque layer.

Where desired, reflecting agent precursor or precursors may be distributed in whole or in part within a processing composition permeable polymeric matrix such as gelatin and/or any other such polymeric matrixes as are specifically denoted throughout the specification as suitable for employment as a matrix binder and may be distributed in one or more of the film unit layers which may be separated or contiguous and should be intermediate the image-receiving layerand dimensionally stable opaque layer, provided that its distribution and concentration is effective to provide the denoted post procesing masking function, and that in whole or in part the resultant generated reflecting agent may be ultimately disposed within the processing composition residuum located intermediate the image-receiving layer and next adjacent silver halide emulsion strata and associated dye image-forming material.

As examples of opacifying agents adapted for employment in the practice of the present invention, mention may be made of opacifying pigments and opacifying dyes and mixtures of such dyes and/or pigments preferably dyes and pigments of black coloration and most preferably black pigments such as carbon black, iron oxide, titanium (III) oxide, titanium (Ill) hydroxide, and the like.

Preferred opacifying agent or agents will possess the maximum opacifying capacity per unit weight, be photographically nondeleterious and substantially nondiffusible during and subsequent to distribution of the processing composition containing same. A particularly preferred opacifying agent has been found to comprise carbon black due to its highly efficient absorption characteristics. In general, a processing composition particularly desired for employment in the practice of the present invention will contain carbon black in a concentration effective, e.g., about 3 to grams of carbon black dispersed in 100 cc. of water, to prevent transmission, through the distributed stratum comprising the composition, of in excess of 95 percent of the actinic radiation incident on the stratum.

In general, preferred agents, both opacifying and reflecting, are those which remain immobile within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiffusible pigment dispersions.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 13, incident on the laminates exposure surface 34, as illustrated in FIG. 2.

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit l0 is processed by being passed through opposed suitably gapped rolls 35 in order to apply compressive pressure to frangible container 11 and to effect rupture of longitudinal seal 30 and distribution of alkaline processing composition 12, possessing an opacifying agent and a pH at which the cyan, magenta and yellow dye developers are soluble and diffusible as a function of the point-to-point degree of exposure of redsensitive silver halide emulsion layer 16, green-sensitive silver halide emulsion layer 19 and blue-sensitive silver halide emulsion layer 22, respectively, intermediate reflecting agent precursor layer 25 and auxiliary layer 23.

Alkaline processing solutionvl2 permeates emulsion layers 16, 19 and 22 to initiate development of the latent images contained in the respective emulsions and reflecting agent precursor layer 25 to initiate generation of reflecting agent. The cyan, magenta and yellow dye developers, of layers l5, l8 and 21, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing irnagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure. At least part of the irnagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to dyeable polymeric layer 24 to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the in situ generated reflecting agent layer 26 which layer effects masking of opacifying agent present in processing composition residuum l2 and cyan, magenta and yellow dye developer remaining associated with blue-sensitive emulsion layer 22, green-sensitive emulsion layer 19 and red-sensitive emulsion layer 16.

Subsequent to distribution of processing solution 12, container 11 may be manually dissociated from the remainder of the film unit, as described above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details therein set forth and are intended to be illustrative only.

Film unit similar to that shown in the drawings may be prepared, for example, by coating, in succession, on a gelatin subbed, 4 mil. opaque polyethylene terephthalate film base, the following layers:

1. a layer of the cyan dye developer 1,4-bis-(fi-[hydroquinonyl-a-methylI-ethylamino)-5,8-dihydroxy-anthraquinone dispersed in gelatin and coated at a coverage of about 150 mgsJft. of dye and about 200 mgs./ft. of gelatin;

2. a red-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 200 mgsJft. of silver and about mgs./ft." of gelatin;

3. a layer of gelatin coated at a coverage of about 200 mgsJftF;

4. a layer of the magenta dye developer 2-(p'[B-hydroquinonylethyl] -phenylazo )-4-isopropoxyl -naphthol dispersed in gelatin and coated at a coverage of 70 mgsjft. of dye and about 100 mgs./ft. of gelatin;

5. a green-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 100 mgslft. of silver and 60 mgs./ft. of gelatin;

6. a layer containing 4'-methylphenyl hydroquinone dispersed in gelatin and coated at a coverage of about 25 mgs./ft. of 4'-methyl-phenyl hydroquinone and about mgslft. of gelatin;

7. a layer of the yellow dye developer 4-(p-[B-hydroquinonylethyl]-phenylazo)-3-(N,n-hexylcarboxamido)-nlphenyl-S-pyrazolone dispersed in gelatin and coated at a coverage of about 40 mgs./ft. of dye and 50 mgs./ft.- of gelatin;

cyan, magenta and yellow dye developer transfers, by diffusion, to aqueous alkaline solution permeable and dyeable polymeric layer 20 to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the in situ generation of reflecting agent in layer 49 which effects masking of yellow, magenta and cyan dye developer associated with the blue-sensitive silver halide emulsion layer, the green-sensitive silver halide emulsion layer and the red-sensitive silver halide emulsion layer subsequent to processing. Subsequent to substantial transfer image formation, a sufficient portion of the ions comprising aqueous alkaline solution 26 transfers, by diffusion, through permeable polymeric spacer layer 29 and to permeable polymeric acid layer 28 whereby alkaline solution 26 decreases in pH, as a function of neutralization, to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are substantially insoluble and nondiffusible, to provide thereby a stable multicolor dye transfer image viewable through dimensionally stable transparent layer 24.

Subsequent to distribution of processing solution 26, container 31, optionally, may be manually dissociated from the remainder of the film unit, as described above.

As previously stated, the multicolor dye transfer image of laminate 32 is viewable through dimensionally stable transparent sheet 24 and that of laminate 33 is viewable through dimensionally stable transparent layer 39 subsequent to transfer image formation, in the preferred embodiments detailed above.

Where desired, transparent sheet 24 of laminate 32, as shown in FIGS. to 10, and/or opaque sheet 40 of laminate 33, as shown in FIGS. 11 to 16, illustrated in the respective figures as a sheet element fixedly maintained, superposed on and coextensive with the surface of the laminate distal opaque support layer and transparent support layer 39, respectively, may in a further embodiment of the present invention, be fixedly positioned extending transverse a leading edge of the laminate and adapted to be superposed on the surface of the laminate prior to, or contemporaneous with, distribution of processing composition 26. In such instance, the dimensionally stable sheet may comprise a flexible sheet material displaced from contact with the surface of laminate 32 and/or 33 during photoexposure and brought into superposed relationship with such surface subsequent to exposure contemporaneous with, or preceding, distribution of processing composition 26 intermediate such sheet and the photoexposed laminate.

As relating to laminate 32, subsequent to processing of the integral film unit, the superposed dimensionally stable sheet may be stripped from the remainder of the film unit alone or in accompaniment with the processing composition where desired. In further embodiments of the present invention, the flexible sheet material when superposed on the surface of the laminate subsequent to photoexposure of laminate 32, may comprise an opaque sheet material and/or the processing composition may retain opacifying agent or agents and either and/or both taken together may possess sufficient opacifying capacity to insure protection of the laminate from actinic radiation incident on that surface of the laminate through which photoexposure was accomplished, which, in combina tion with opaque support layer 10 of the laminate, provides a structure adapted to be processed in the presence of actinic radiation. Subsequent to the processing of such film unit, the superposed dimensionally stable sheet may be stripped from the remainder of the film unit, where desired or opaque, alone or in accompaniment with the processing composition, where desired or opaque, to reveal the dye transfer image carried by the laminate. Displacement of the flexible sheet may be manually effected alone or together with processing composition residuum where desired by selective adhesion to, or release of the processing composition from, the manually displaced sheet element.

It will also be recognized that substitution of a dimensionally stable transparent support layer, in replacement for the opaque support layer 10 of laminate 32, exposes to viewing the dye image present in the photosensitive silver halide emulsion and associated dye developer layers which is negative with respect to the dye transfer image carried by imagereceiving layer 20 and may be viewed against reflecting layer 45 which masks the dye transfer image from observation through such transparent support layer.

With respect to laminate 33, the processing composition need not, but may, retain opacifying agent or agents, as previously noted, for the purposes of further opacification capacity an in such instance opaque sheet 39 may be optionally replaced by a translucent or transparent sheet material. In those instances where it is desired to view the dye image present in the photosensitive silver halide emulsion and associated dye developer layers, which is negative with respect to the dye transfer image carried by the image-receiving layer, against the masking background of reflecting layer 45, the sheet material and processing composition employed may be transparent for viewing purposes.

Analogous to aforementioned description regarding laminate 32, the dimensionally stable sheet may be stripped from the remainder of the film unit alone or in combination with the processing composition and especially where either the sheet and/or the processing composition is opaque and it is desired to view the aforementioned negative dye image.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details herein set forth and are intended to be illustrative only.

Film units similar to that set forth in the drawings may be prepared, for example, by coating, in succession, on an opaque, 4-mil polyethylene terephthalate film base:

1. a layer of the cyan dye developer l,4-bis-( [B-hydroquinonyl-a-methyl]-ethyl-amino)-5,8-dihydroxy-anthraquinone dispersed in gelatin and coated at a coverage ofabout I50 mgs./ft. of dye and about 200 mgs./ft. of gelatin;

2. a red-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 200 mgs./ft. of silver and about mgs./ft. of gelatin;

3. a layer of gelatin coated at a coverage of about 200 mgs./ft.

4. a layer of the magenta dye developer 4-isopropoxy-2'l p- (B-hydroquinonyl ethyl) phenylazol-naphthalene-lethoxy acetate dispersed in gelatin and coated at a coverage of about 70 mgs./ft. of dye and about 100 mgs./ft. of gelatin;

. a green-sensitive gelatino silver halide emulsion coated at a coverage of about lOO mgs./ft. of silver and about 60 mgs./ft. of gelatin;

6. a layer of gelatin coated at a coverage of about I50 7. a layer of the yellow dye developer 4-(p-[B-hydroquinonyl ethyllphenylazo)-3-(N-n-hexylcarboxamido)-l-phenyl-5-pyrazolone dispersed in gelatin and coated at a coverage of about 40 mgs./ft. of dye and about 50 mgs./ft. of gelatin;

8. a blue-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 60 mgs./ft. of silver and about 50 mgs./ft. of gelatin;

9. a layer containing 4-methylphenyl hydroquinone dispersed in gelatin and coated at a coverage of about l0 mgs./ft. of 4'-methylphenyl hydroquinone and about 30 mgs./ft." of gelatin;

10. a dispersion of barium chloride in gelatin coated at a coverage of approximately 900 mgsjft. barium chloride and of approximately mgs./ft. gelatin to provide a polymeric reflecting agent precursor layer approximately 0.25 mil thick; and

l 1. a 2:1 mixture, by weight, of polyvinyl alcohol and poly- 4-vinylpyridine, at a coverage of approximately 600 mgs./ft. to provide a polymeric image-receiving layer approximately 0.40 mil thick.

LII

Transparent polyethylene terephthalate sheet may then be superposed on the external surface of coating No. l 1 and the two components then taped together, in composite form, at their respective edges by means of pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant film unit.

A rupturable container comprising an outer layer of paper, an intermediate layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution comprising:

Water I cc. Potassium hydroxide ll.2 grams Hydroxyethyl cellulose (high 3,4 grams viscosity) [commercially available from Hercules Powder Co., Wilmington, Delaware, under the trade name Natrasol 250 I N-benzyl-a-picolinium bromide l.5 grams Benzotriazole l.() gram Sodium sulfate 107 grams may then be fixedly mounted on the leading edge, of each of the composites, by pressure-sensitive tapes interconnecting the respective containers and laminates, such that upon application of compressive pressure to the container its contents will be distributed, upon rupture of thecontainers marginal seal, intermediate the transparent polyethylene terephthalate sheet and the next adjacent layer.

The photosensitive laminates may be exposed through step wedges to selectively filtered radiation incident on the transparent polyethylene terephthalate sheet and processed by passage of the exposed film unit through suitably gapped opposed rolls, to effect rupture of the container and distribution of the containers contents between the photosensitive element and the sheet element. Subsequent to processing, a multicolor dye transfer image formation may be viewed through the transparent polyethylene terephthalate sheet and such image formation is found to be substantially completed and exhibiting the required color brilliance, hues, saturation and isolation within a period of about 1 to 3 minutes.

As an illustrative construction of the novel film units of the present invention employing the aforementioned metathetical generation of reflecting agent in situ, the barium chloride precursor of layer immediately above may be replaced with a dispersion of barium sulfide in gelatin coated, as above, at an average of approximately 725 mgs./ft. barium sulfide and of approximately 150 mgs./ft. gelatin and the sodium sulfate precursor of the processing composition may be replaced with 12.2 grams of zinc sulfate to effectively provide the simultaneous in situ generation of both barium sulfate and zinc sulfide reflecting agent pigments, intermediate the image-receiving layer of the film unit and auxiliary layer 9, during processing of a photoexposed film unit.

The pH of the alkaline processing solution initially employed must be a pH at which the dye developers employed are soluble and diffusible. Although it has been found that the specific pH to be employed may be readily determined empirically for any dye developer, or group of dye developers, most particularly desirable dye developers are soluble at pH s above 9 and relatively insoluble at pHs below 9, in reduced form, and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiments detailed, will include the stated film-forming viscosity-increasing agent or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition. In the latter instance, however, it will be preferred that the concentration of solvent, that is, water, etc., comprising the composition be the minimum amount necessary to conduct the desired transfer process, in order to adversely effect the structural integrity of the laminate and that the layers forming the laminate can readily accommodate and dissipate the solvent throughout during film unit of the present invention, to provide reduction of the alkalinity of the film unit from a pH at which the dyes are soluble to a pH at which the dyes are substantially nondiffusible, in order to advantageously stabilize the dye transfer image. In such instance, a polymeric acid layer such as that obtained by coating the polyethylene terephthalate film base with the partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing, for 14 hours, about 300 grams of high viscosity poly-(ethylene/maleic anhydride), about 140 grams of n-butyl, alcohol and about 1 cc. of percent phosphoric acid to provide a polymeric acid layer approximately 0.75 mil thick preferably in turn overcoated with a 2:1 solution of hydroxypropyl cellulose and polyvinyl alcohol in water to provide a polymeric spacer layer approximately 0.25 mil thick, will be positioned intermediate the common support and next adjacent essential layer, as previously described.

As disclosed in aforementioned US. Pat No. 3,362,819 the presence of an inert spacer layer was found to be effective in evening out the various reaction rates over a wide range of temperatures, for example, by preventing premature pH reduction when imbibition is effected at temperatures above room temperature, for example, at to F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture inthe polymeric acid layer becomes a function of the alkali diffusion rates.

However, as disclosed in copending US. Pat. application Ser. No 664,503, filed Aug. 30, I967 in the names of Leonard C. Farney, Howard G. Rogers and Richard W. Young, now US. Pat. 3,455,686, issued July 15, 1969 preferably the aforementioned rate at which the cations of the alkaline processing composition, i.e., alkali ions, are available for capture in the polymeric acid layer should, be decreased with increasing transfer processing temperatures in order to provide diffusion transfer color processes relatively independent of positive transfer image variations over an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusion rate of alkali through a permeable inert polymeric spacer layer increases with increased processing temperature to the extent, for example, that at relatively high transfer processing temperatures, that is, transfer processing temperatures above approximately 80 F., a premature decrease in the pH of the transfer processing composition occurs due, at least in part, to the rapid diffusion of alkali from the dye transfer environment and its subsequent neutralization upon contact with the polymeric acid layer. This was stated to be especially true of alkali traversing an inert spacer layer possessing permeability to alkali optimized to be effective within the temperature range of optimum transfer processing. Conversely, at temperatures below the optimum transfer processing range, for example, temperatures below approximately 40 F., the last-mentioned inert spacer layer was disclosed to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates and to result in maintenance of the transfer processing environments high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.

It is further stated in the last-mentioned copending application Ser. No. 664,503 to have been found, however, that if the inert spacer layer of the print-receiving element is replaced by a spacer layer which comprises a permeable polymeric layer exhibiting permeability inversely dependent on temperature, that is, a polymeric film-forming material which exhibits decreasing permeability to solubilized alkali derived cations such as alkali metal and quantemary ammonium ions under conditions of increasing temperature, that the positive transfer image defects resultant from the aforementioned overextended pH maintenance and/or premature pH reduction are obviated.

As examples of polymers which were disclosed to exhibit inverse temperature-dependent permeability to alkali, mention may be made of: hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyvinyl oxazolidone, hydroxypropyl methyl cellulose, iospropyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal, partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated to generally comprise saturated aliphatic hydrocarbon chains of a molecular weight of at least 1,000, preferably of about 1,000 to 50,000, possessing a degree of acetalation within about to 30 percent, 10 to 30 percent, 20 to 80 percent, and 10 to 40 percent, of the polyvinyl alcohols theoretical polymeric hydroxy groups, respectively, and including mixed acetals where desired.

Where desired, a mixture of the polymers is to be employed, for example, a mixture of hydroxypropyl methyl cellulose and partial polyvinyl butyral.

Employment of the detailed and preferred film units of the present invention, according to the herein described color diffusion transfer process, specifically provides for the production of a highly stable transfer image accomplished, at least in part, by effectively obviating the previously discussed disadvantages of the prior art products and processes, by in process adjustment of the environmental processing from a condition at which dye diffusion or transfer is operative to a condition at which dye transfer is substantially inoperative subsequent to substantial transfer image formation. The stable color transfer image is obtained irrespective of the fact that the film unit is maintained as an integral laminate unit during exposure, processing, viewing, and storage of the unit. Accordingly, by means of the present invention, multicolor transfer images may be provided over an extended processing temperature range which exhibit desired maximum and minimum dye transfer image densities; yellow, magenta and cyan dye saturation; red, green and blue hues; and color separation. These unexpected advantages are in addition to the manufacturing advantages obtained by reason of the present inventions integral color transfer film unit and which will be readily apparent from examination of the units parameters, that is, for example, advantages in more efficient utilization of fabricating materials and components, enhanced simplicity of film manufacture and camera design and construction, and more simplified and effectively controlled customer utilization of the unit.

The dimensionally stable support layers referred to may comprise any of the various type of conventional opaque and transparent rigid or flexible materials possessing the support and optional characteristics denoted above, and may comprise polymeric films of both synthetic types and those derived from naturally occurring products. Particularly suitable materials include aqueous alkaline solution impermeable, water vapor permeable, flexible polymeric materials such as vapor permeable polymeric films derived from ethylene glycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate; polyamides; polymethacrylic acid methyl and ethyl esters; cellulose derivatives such as cellulose, acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetate-butyrate; alkaline solution impermeable, water vapor permeable papers; crosslinked polyvinyl alcohol; regenerated cellulose; and the like.

It will be noted that the liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, pbenzylaminophenyl, hydroquinone, toluhydroquinone, phenylhydroquinone, 4-methylphenylhydroquinone, etc. It is also contemplated to employ a plurality of auxiliary or accelerating developing agents, such as a 3-pyrazolidone developing agent and a benzcnoid developing agent, as disclosed in U.S. Pat. No. 3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of l-phenyl-3-pyrazolidone. in combination with p benzylaminophenol and 1-phenyl-3-pyrazolidone in combination with 2,5-bis-ethylenimino-hydroquinone. Such auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the image-receiving layer, or in any other auxiliary layer or layers, of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energytransfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxiliary developing agent for further reaction with the exposed silver halide.

In addition, development may be effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in U.S. Pat. No. 3,173,786, issued Mar. 16, 1965.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the pH and solvent concentration required. When desirable it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/or in the photosensitive emulsion.

In all examples of this specification, percentages of components are given by weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffusion transfer processes is set forth in aforementioned U.S. Pat. No. 2,983,606 and in the various copending U.S. applications referred to in that patent, especially in the table of U.S. applications incorporated by reference into the patent as detailed in column 27. As examples of additional U.S. patents detailing specific dye developers for photographic transfer process usc, mention may also be made of U.S. Pat. Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl cellulose, as disclosed in U.S. Pat. No. 2,992,104; an acylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in U.S. Pat. No. 3,043,692; polymers of N-alkyl-a,B-unsaturated carboxamides and copolymers of N- alkyl-a, B-carboxamides with N-hydroxyalkyl-a,B-unsaturated carboxamides, as disclosed in U.S. Pat. No. 3,069,263; copolymers of vinylphthalimide and a,B-unsaturated carboxylic acids, as disclosed in U.S. Pat. No. 3,061,428; copolymers of N-vinylpyrrolidones and a,B-unsaturated carboxylic acids and terepolymers of N-vinyl pyrrolidones, a,B-unsaturated carboxylic acids and alkyl esters of a,B-unsaturated carboxylic acids, as disclosed in U.S. Pat. No. 3,044,873; copolymers of N,N-dialkyl-a,B-unsaturated carboxamides with a,B-unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N-aryland N-cycloalkyl-a,B-unsaturated carboxamides with afi-unsaturated carboxylic acids, as disclosed in U.S. Pat. No. 3,069,264; and the like.

In addition to conventional techniques for the direct dispersion of a particulate solid material in the polymeric, or colloidal, matrix such as ball-milling and the like techniques, the preparation of the dye developer dispersion may also be obtained by dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solution distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents possesses a sufficicntly low boiling point or washing where the selected solvent, or solvents, possesses a sufficiently high differential solubility in the wash medium, for example, water, when measured against the solubility of the remaining composition components, and/or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types referred to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic colorproviding materials in polymeric binders, specifically for the formation component layers of photographic film units, reference may be made to U.S. Pat. Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

Although the invention has been discussed in detail throughout employing dye developers, the preferred dye image-providing materials, it will be readily recognized that other, less preferred, dye image-providing materials may be substituted in replacement of the preferred dye developers in the practice of the invention. For example, there may be employed dye image-forming materials such as those disclosed in US. Pat. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735; 3,148,062; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294; 3,330,655; 3,347,671; 3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943; etc., wherein color diffusion transfer processes are described which employ color coupling techniques comprising, at least in part, reacting one or more color developing agents and one or more color formers or couplers to provide a dye transfer image to a superposed image-receiving layer and those disclosed in U.S. Pat. Nos. 2,774,668 and 3,087,817, wherein color diffusion transfer processes are described which employ the imagewise differential transfer of complete dyes by the mechanisms therein described to provide a transfer dye image to a contiguous image-receiving layer, and thus including the employment of image-providing materials in whole or in part initially insoluble or nondiffusible as disposed in the film unit which diffuse during processing as a direct or indirect function of exposure.

For the production of the photosensitive gelatino silver halide emulsions employed to provide the film unit, the silver halide crystals may be prepared by reacting a water-soluble silver salt, such as silver nitrate, with at least one water-soluble halide, such as ammonium, potassium or sodium bromide, preferably together with a corresponding iodide, in an aqueous solution of a peptizing agent such as a colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual water-soluble salts by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or alternatively, employing any of the various flocc systems, or procedures, adapted to effect removal or undesired components, for example, the procedures described in US. Pat. Nos. 2,614,928; 2,614,929; 2,728,662; and the like; afterripening the dispersion at an elevated temperature in combination with the addition of gelatin and various adjuncts, for example, chemical sensitizing agents of US. Pat. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. 3., Photography Its Materials and Processes, 6th Ed. 1962.

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, as previously described, preferably comprise a crystal of silver, for example, one or more of the silver halides such as silver chloride, silver iodide, silver bromide, or mixed silver halides such as silver chlorobromide or silver iodobromide, of varying halide ratios and varying silver concentrations.

As the binder for the respective emulsion strata, the aforementioned gelatin may be, in whole or in part, replaced with some other colloidal material such as albumin; casein; or zein; or resins such as a cellulose derivative, as described in U.S. Pat. Nos. 2,322,085 and 2,327,808; polyacrylamides, as described in US. Pat. No. 2,541,474; vinyl polymers such as described in an extensive multiplicity of readily available US. and foreign patents.

Although the preceding description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in contiguous coplanar relationship and, specifically, in terms of the preferred tripack-type structure comprising a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a bluesensitive silver halide emulsion stratum having associated therewith, respectively, a cyan dye developer, in magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associatedtherewith, for example, an appropriate dye developer in or behind its respective silver halide emulsion portion. In general, a suitable photosensitive screen will comprise minute red-sensitized emulsion elements, minute green-sensitized emulsion ele ments and minute blue-sensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black and white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression positive image" has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the imagecarrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image," assume that the photosensitive element is exposed to actinic light through a negative transparency. ln this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be a negative. The expression positive image" is intended to cover such an image produced on the image-carrying layer.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic film unit which comprises a photosensitive laminate containing, as essential layers, a dimensionally stable common support carrying on one surface, a dyeable polymeric layer and a photosensitive silver halide emulsion layer having associated therewith a dye image-forming material which is processing composition diffusible, as a function of the point-to-point degree of the emulsions exposure to actinic radiation, the improvement which comprises a layer permeable to processing composition solubilized dye image-forming material comprising light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer in a quantity effective to mask said dye image-forming material associated with said photosensitive silver halide emulsion layer subsequent to processing.

2. A photographic film unit as defined in claim 1 wherein said dyeable polymeric layer is processing composition permeable and said film unit additionally includes an acidic layer, containing sufficient substantially nondiffusible acid reagent to effect reduction of a processing composition having a first pH at which said dye image-forming material is soluble and diffusible to a second pH at which said material is substantially insoluble and nondiffusible, positioned intermediate said dimensionally stable common support and next adjacent essential layer.

3. A photographic film unit as defined in claim 2 including a processing composition permeable polymeric spacer layer positioned intermediate said acidic layer and said next adjacent essential layer. 7

4. A photographic film unit as defined in claim 1 wherein said dye image-providing material is a dye which is a silver halide developing agent.

5. A photographic film unit as defined in claim 1 wherein said dimensionally stable common support is opaque and said photosensitive silver halide emulsion layer is positioned intermediate said support and said dyeable polymeric layer.

6. A photographic film unit as defined in claim 5 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a transparent dimensionally stable sheet superposed substantially coextensive the surface of said laminate opposite said dimensionally stable opaque support and a rupturable container retaining a processing composition fixedly positioned and extending transverse a leading edge of said photosensitive laminate and adapted to effect unidirectional discharge of said containers contents intermediate said sheet and said laminate.

7. A photographic film unit as defined in claim 1 wherein said dimensionally stable common support is transparent and said dyeable polymeric layer is positioned intermediate said support and said photosensitive silver halide emulsion layer.

8. A photographic film unit as defined in claim 7 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a dimensionally stable sheet superposed substantially coextensive the surface of said laminate opposite said dimensionally stable transparent common support and a rupturable container retaining a processing composition fixedly positioned and extending transverse a leading edge of said photosensitive laminate and adapted to effect unidirectional discharge of said containers contents intermediate said sheet and said laminate.

9. A photographic film unit as defined in claim 8 wherein said dimensionally stable sheet is opaque.

10. A photographic film unit as defined in claim 8 wherein said dimensionally stable sheet is superposed in substantially coextensive relationship to the surface of said silver halide emulsion layer and associated dye image-forming material and said processing composition contains dispersed therein an opacifying agent.

11. A photographic film unit as defined in claim I which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a separate dimensionally stable sheet having a leading edge fixedly positioned extending transverse a leading edge of said laminate and adapted to be superposed subsequent to photoexposure of said laminate substantially coextensive the surface of said laminate opposite said dimensionally stable common support and a rupturable container retaining a processing composition and extending transverse said leading edge of said photosensitive laminate intermediate said sheet and said laminate and adapted to effect unidirectional distribution of said containers contents intermediate said sheet and said laminate upon superpositioning of said sheet on said surface of said laminate.

12. A photographic film unit as defined in claim 11 wherein said dimensionally stable sheet is opaque and is adapted to be superposed subsequent to photoexposure in substantially coextensive relationship to the surface of said laminate opposite said dimensionally stable common support, said common support is transparent, and said dyeable polymeric layer is positioned intermediate said support and said photosensitive silver halide emulsion layer.

13. A photographic film unit as defined in claim 11 wherein said dimensionally stable sheet is transparent and is adapted to be superposed subsequent to photoexposure in substantially coextensive relationship to the surface of said laminate opposite said dimensionally stable common support, said common support is opaque, and said photosensitive silver halide emulsion layer is positioned intermediate said support and said dyeable polymeric layer.

14. A photographic film unit as defined in claim l3 wherein said reflecting agent precursor is barium ions and said processing composition contains sulfate ions adapted to react during processing with said barium ions to provide substantially white, inorganic, visible light-reflecting barium sulfate pigment.

15. A photographic film unit as defined in claim 14 wherein said barium ions and said sulfate ions are present in substantially stoichiometric quantities effective to provide barium sulfate reflecting agent coverage of from about 200 to 1,000 mgs./ft. barium sulfate.

16. In a photographic film unit as defined in claim 4 which includes, in combination:

a photosensitive laminate containing, as essential layers, at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes soluble and diffusible, in alkali, at a first pH, as a function of exposure of its associated silver halide emulsion layer, an alkaline solution permeable transparent polymeric layer dyeable by said dyes, a dimensionally stable alkaline solution impermeable support layer, and an alkaline solution permeable transparent acidic layer containing sufficient acidifying groups to effect reduction of the processing solution having said first pH to a second pH at which said dyes are insoluble and nondiffusible positioned intermediate said dimensionally stable support layer and the essential layer next adjacent thereto; the improvement which comprises a layer, permeable to solubilized dye and positioned inter- 

2. A photographic film unit as defined in claim 1 wherein said dyeable polymeric layer is processing composition permeable and said film unit additionally includes an acidic layer, containing sufficient substantially nondiffusible acid reagent to effect reduction of a processing composition having a first pH at which said dye image-forming material is soluble and diffusible to a second pH at which said material is substantially insoluble and nondiffusible, positioned intermediate said dimensionally stable common support and next adjacent essential layer.
 3. A photographic film unit as defined in claim 2 including a processing composition permeable polymeric spacer layer positioned intermediate said acidic layer and said next adjacent essential layer.
 4. A photographic film unit as defined in claim 1 wherein said dye image-providing material is a dye which is a silver halide developing agent.
 5. A photographic film unit as defined in claim 1 wherein said dimensionally stable common support is opaque and said photosensitive silver halide emulsion layer is positioned intermediate said support and said dyeable polymeric layer.
 6. A photographic film unit as defined in claim 5 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a transparent dimensionally stable sheet superposed substantially coextensive the surface of said laminate opposite said dimensionally stable opaque support and a rupturable container retaining a processing composition fixedly positioned and extending transverse a leading edge of said photosensitive laminate and adapted to effect unidirectional discharge of said container''s contents intermediate said sheet and said laminate.
 7. A photographic film unit as defined in claim 1 wherein said dimensionally stable common support is transparent and said dyeable polymeric layer is positioned intermediate said support and said photosensitive silver halide emulsion layer.
 8. A photographic film unit as defined in claim 7 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a dimensionally stable sheet superposed substantially coextensive the surface of said laminate opposite said dimensionally stable transparent common support and a rupturable container retaining a processing composition fixedly positioned and extending transverse a leading edge of said photosensitive laminate and adapted to effect unidirectional discharge of said container''s contents intermediate said sheet and said laminate.
 9. A photographic film unit as defined in claim 8 whErein said dimensionally stable sheet is opaque.
 10. A photographic film unit as defined in claim 8 wherein said dimensionally stable sheet is superposed in substantially coextensive relationship to the surface of said silver halide emulsion layer and associated dye image-forming material and said processing composition contains dispersed therein an opacifying agent.
 11. A photographic film unit as defined in claim 1 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members, including a separate dimensionally stable sheet having a leading edge fixedly positioned extending transverse a leading edge of said laminate and adapted to be superposed subsequent to photoexposure of said laminate substantially coextensive the surface of said laminate opposite said dimensionally stable common support and a rupturable container retaining a processing composition and extending transverse said leading edge of said photosensitive laminate intermediate said sheet and said laminate and adapted to effect unidirectional distribution of said container''s contents intermediate said sheet and said laminate upon superpositioning of said sheet on said surface of said laminate.
 12. A photographic film unit as defined in claim 11 wherein said dimensionally stable sheet is opaque and is adapted to be superposed subsequent to photoexposure in substantially coextensive relationship to the surface of said laminate opposite said dimensionally stable common support, said common support is transparent, and said dyeable polymeric layer is positioned intermediate said support and said photosensitive silver halide emulsion layer.
 13. A photographic film unit as defined in claim 11 wherein said dimensionally stable sheet is transparent and is adapted to be superposed subsequent to photoexposure in substantially coextensive relationship to the surface of said laminate opposite said dimensionally stable common support, said common support is opaque, and said photosensitive silver halide emulsion layer is positioned intermediate said support and said dyeable polymeric layer.
 14. A photographic film unit as defined in claim 13 wherein said reflecting agent precursor is barium ions and said processing composition contains sulfate ions adapted to react during processing with said barium ions to provide substantially white, inorganic, visible light-reflecting barium sulfate pigment.
 15. A photographic film unit as defined in claim 14 wherein said barium ions and said sulfate ions are present in substantially stoichiometric quantities effective to provide barium sulfate reflecting agent coverage of from about 200 to 1,000 mgs./ft.2 barium sulfate.
 16. In a photographic film unit as defined in claim 4 which includes, in combination: a photosensitive laminate containing, as essential layers, at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes soluble and diffusible, in alkali, at a first pH, as a function of exposure of its associated silver halide emulsion layer, an alkaline solution permeable transparent polymeric layer dyeable by said dyes, a dimensionally stable alkaline solution impermeable support layer, and an alkaline solution permeable transparent acidic layer containing sufficient acidifying groups to effect reduction of the processing solution having said first pH to a second pH at which said dyes are insoluble and nondiffusible positioned intermediate said dimensionally stable support layer and the essential layer next adjacent thereto; the improvement which comprises a layer, permeable to solubilized dye and positioned intermediate said dyeable polymeric layer and the silver halide emulsion layer next adjacent thereto, which includes light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to intEract with second ionic species to provide a substantially white, inorganic light-reflecting agent effective to mask said dyes associated with said silver halide emulsion layer subsequent to processing.
 17. A photographic film unit as defined in claim 16 including a dimensionally stable sheet superposed coextensive the surface of the laminate opposite said dimensionally stable support layer and a rupturable container retaining an aqueous alkaline processing solution, having said first pH, fixedly positioned and extending transverse said leading edge of said laminate to effect unidirectional discharge of the container''s contents coextensive the surface of the laminate intermediate said laminate and said sheet.
 18. A photographic film unit as defined in claim 16 wherein each of said selectively sensitized photosensitive silver halide emulsion layers has predominant spectral sensitivity to separate regions of the spectrum and subsequent to photoexposure of said laminate the dye associated with each of said silver halide emulsion layers possesses, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.
 19. A photographic film unit as defined in claim 18 wherein each of said silver halide emulsion layers and its associated dye is separated from the next adjacent silver halide emulsion layer and its associated dye by an alkaline solution permeable polymeric interlayer.
 20. A photographic film unit as defined in claim 17 wherein said dimensionally stable sheet is opaque and is superposed next adjacent the silver halide emulsion layer and associated dye distal said dimensionally stable support layer of said laminate and said support layer is transparent.
 21. In a photographic film unit as defined in claim 20 which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members and which comprises, in combination: a photosensitive laminate containing, in sequence, a red-sensitive silver halide emulsion layer having associated therewith a cyan dye, a green-sensitive silver halide emulsion layer having associated therewith a magenta dye; a blue-sensitive silver halide emulsion layer having associated therewith a yellow dye, each of said cyan, magenta and yellow dyes being silver halide developing agents and being soluble and diffusible, in alkali, at a first pH, as a function of the exposure of its associated silver halide emulsion layer, an alkaline solution permeable transparent polymeric layer dyeable by said dyes, an alkaline solution permeable transparent polymeric acid layer containing sufficient acidifying groups to effect reduction of a processing solution having said first pH to a second pH at which said dyes are substantially insoluble and nondiffusible, and a dimensionally stable alkaline solution impermeable transparent support; a dimensionally stable opaque sheet fixedly maintained superposed substantially coextensive the surface of the laminate opposite said transparent support; and a rupturable container retaining an aqueous alkaline processing solution, having said first pH, fixedly positioned and extending transverse a leading edge of said photosensitive element to effect unidirectional discharge of the container''s contents intermediate said laminate and said opaque sheet upon application of compressive force to said container; the improvement which comprises disposing intermediate said dyeable polymeric layer and said blue-sensitive silver halide emulsion layer an alkaline solution solubilized dye permeable polymeric layer containing light-reflecting precursor which comprises, upon contact with said processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent in a concentration sufficient to mask cyan, magenta and yellow dye associated with said red-, green- and blue-sensitive Silver halide emulsion layers subsequent to processing of the film unit.
 22. A photographic film unit as defined in claim 21 wherein said pigment precursor comprises barium ions and said processing solution includes sulfate ions.
 23. A photographic film unit as defined in claim 21 wherein said first pH is above 9 and said second pH is below
 9. 24. In a process of forming transfer images in color which comprises, in combination, the steps of: a. exposing a photographic film unit which includes, in combination, a photosensitive laminate containing, as essential layers, a photosensitive silver halide emulsion layer having associated therewith a dye image-providing material, a polymeric layer dyeable by said image-providing material, and a dimensionally stable common support layer; b. contacting said exposed film unit with a processing composition; c. effecting thereby development of said silver halide emulsion; d. forming thereby an imagewise distribution of mobile dye image-providing material, as a function of the point-to-point degree of emulsion exposure; e. transferring, by diffusion, at least a portion of said imagewise distribution of mobile dye image-providing material to said polymeric layer dyeable by said dye image-providing material to provide a dye image thereto in terms of said imagewise distribution; and f. maintaining said laminate intact subsequent to said processing; the improvement which comprises a layer permeable to processing composition solubilized dye image-providing material which includes light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent in a concentration sufficient to mask said dye image-providing material associated with said photosensitive silver halide emulsion layer subsequent to processing intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer and effecting thereby interaction between said first and said second ionic species upon contact of said layer including said light-reflecting agent precursor and said processing composition to provide said substantially white, inorganic visible light-reflecting agent intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer.
 25. A process of forming transfer images in color as defined in claim 24 wherein said dimensionally stable support layer is opaque to incident actinic radiation, said photosensitive silver halide emulsion layer is positioned intermediate said support and said dyeable polymeric layer, said film unit is contacted with incident exposing actinic radiation at the surface of said film unit opposite said support, and said film unit is contacted with said processing composition at the surface of said film unit opposite said support.
 26. In a process of forming transfer images in color as defined in claim 24 which comprises, in combination, the steps of: a. exposing a photographic film unit which is adapted to be processed by passing the unit between a pair of juxtaposed pressure-applying members and which includes, in combination: a photosensitive laminate containing, as essential layers, a photosensitive silver halide emulsion layer having associated therewith dye image-providing material which is soluble and diffusible, at a first pH, as a function of silver halide emulsion layer exposure, a processing solution permeable polymeric layer dyeable by said image-providing material, a dimensionally stable support layer, and a permeable acidic layer containing sufficient acidifying groups to effect reduction of a processing solution having said first pH to said second pH at which said dye image-providing material is substantially nondiffusible positioned intermediate said dimensionally stable support layer and next adjacent essential laYer; a dimensionally stable sheet superposed coextensive the surface of the laminate opposite the dimensionally stable support layer; and a rupturable container retaining an aqueous processing solution, having said first pH, fixedly positioned and extending transverse a leading edge of said photosensitive laminate to effect unidirectional discharge of the container''s contents intermediate said dimensionally stable sheet and the surface of said laminate opposite said support layer upon application of compressive force to said container; b. applying compressive force to said rupturable container to effect unidirectional discharge of the container''s aqueous processing solution coextensive said surface of said laminate opposite said support layer and intermediate said laminate and said dimensionally stable sheet; c. effecting thereby development of said silver halide emulsion; d. forming thereby an imagewise distribution of mobile dye image-providing material, as a function of the point-to-point degree of emulsion exposure; e. transferring, by diffusion, at least a portion of said imagewise distribution of mobile dye image-providing material to said processing solution permeable polymeric layer dyeable by said dye image-providing material to provide a dye image thereto in terms of said imagewise distribution; f. transferring, by diffusion, subsequent to substantial transfer image formation, a sufficient portion of the ions of said processing solution to said permeable polymeric acid layer to thereby reduce the alkalinity of said processing solution to said second pH; and g. maintaining said laminate intact subsequent to said processing; the improvement which comprises a processing solution solubilized dye image-providing material permeable layer which includes light-reflecting agent precursor which comprises, upon contact with said processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent in a concentration sufficient to mask said dye image-providing material associated with said photosensitive silver halide emulsion subsequent to processing positioned intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer and associated dye image-providing material and effecting thereby interaction between said first and said second ionic species upon contact of said light-reflecting agent precursor layer with said processing composition to provide said substantially white, inorganic visible light-reflecting agent intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer.
 27. A process as defined in claim 26 including the step of separating said container from the laminate subsequent to substantial transfer image formation.
 28. A process as defined in claim 26 wherein said aqueous alkaline solution additionally contains a film-forming polymeric material.
 29. A process as defined in claim 26 wherein said light-reflecting agent precursor comprises barium sulfide and said alkaline solution includes zinc sulfate.
 30. A process as defined in claim 26 wherein said photosensitive silver halide emulsion layer and associated dye image-providing material is positioned in said laminate distal said dimensionally stable support layer, said support layer is transparent to incident actinic radiation, said dimensionally stable sheet is opaque to incident actinic radiation, and said film unit is contacted with exposing actinic radiation incident on said transparent support layer.
 31. A process as defined in claim 26 wherein said dimensionally stable sheet is opaque to actinic radiation, said dimensionally stable layer is transparent to actinic radiation and said photosensitive silver halide emulsion layer and associated dye image-providing material is positioned in said laminate distal said dimensionally stable transparent support layer, and including the sTep of superposing said sheet coextensive the surface of said laminate opposite said dimensionally stable transparent support layer subsequent to exposure of said laminate and preceding distribution of said processing solution coextensive the surface of the laminate.
 32. A process as defined in claim 24 wherein said dye image-providing material is a dye which is a silver halide developing agent.
 33. In a process of forming transfer images in color, as defined in claim 32, which comprises, in combination, the steps of: a. exposing a photographic film unit which includes, in combination: a photosensitive laminate containing at least two selectively sensitized silver halide emulsion strata, each of said silver halide emulsions having associated therewith a dye, which is a silver halide developing agent, of predetermined color, and is soluble and diffusible in processing composition as a function of the exposure of its associated silver halide emulsion, a polymeric layer dyeable by said dye, and a dimensionally stable support layer; b. contacting said exposed film unit with a processing composition; c. effecting thereby development of each of said silver halide emulsions; d. immobilizing the dye associated with each of said emulsions as a result of development; e. forming an imagewise distribution of mobile dye, as a function of the point-to-point degree of emulsion exposure; f. transferring, by imbibition, at least a portion of each of said imagewise distributions of mobile dye to said alkaline solution permeable polymeric layer dyeable by said dyes to provide thereto a dye image; and g. maintaining the laminate intact subsequent to processing; the improvement which comprises a processing solution solubilized dye permeable layer which includes light-reflecting agent precursor which comprises, upon contact with said processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent in a concentration sufficient to mask said dyes associated with said photosensitive silver halide emulsion strata subsequent to processing positioned intermediate said dyeable polymeric layer and the photosensitive silver halide stratum next adjacent thereto and effecting thereby interaction between said first and said second ionic species upon contact of said light-reflecting agent precursor layer with said processing composition thereby providing said substantially white, inorganic visible light-reflecting agent intermediate said dyeable polymeric layer and said photosensitive silver halide emulsion layer next adjacent thereto.
 34. A process as defined in claim 33 wherein each of said selectively sensitized silver halide emulsion strata has predominant spectral sensitivity to a separate region of the spectrum and, subsequent to exposure, the dye associated with each of said emulsion strata has a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.
 35. A process as defined in claim 34 wherein said dimensionally stable support layer is opaque to incident actinic radiation, said selectively sensitized silver halide emulsion layers are positioned intermediate said dyeable polymeric layer and said opaque support layer, said film unit is exposed by contact with actinic radiation incident on the surface of the film unit opposite said opaque support layer, and said selectively exposed film unit is contacted with said processing composition at said surface opposite said opaque support layer.
 36. A process as defined in claim 34 wherein said film unit includes an alkaline processing composition permeable polymeric acid layer containing sufficient acidifying groups to effect reduction of a processing composition having a first pH at which said dyes are soluble and diffusible to a second pH at which said dyes are substantially insoluble and nondiffusible positioned intermedIate said dimensionally stable support layer and the essential layer next adjacent thereto.
 37. A process as defined in claim 36 wherein said film unit includes a dimensionally stable sheet positioned on the surface of the laminate opposite said dimensionally stable support layer, and a rupturable container retaining an aqueous alkaline processing composition having said first pH fixedly positioned and extending transverse a leading edge of said laminate to effect unidirectional discharge of the container''s contents on the surface of the laminate opposite the dimensionally stable support layer upon application of compressive force to the container, and including the steps of applying compressive force to the rupturable container, subsequent to exposure of the laminate, to effect unidirectional discharge of the container''s aqueous alkaline processing composition intermediate said sheet and said laminate and, subsequent to substantial dye transfer image formation, transferring, by imbibition, a sufficient portion of the ions of said aqueous alkaline processing composition to said polymeric acid layer to thereby reduce the alkalinity of said composition from said first pH to said second pH.
 38. A process as defined in claim 37 wherein said dimensionally stable support layer is transparent, said dimensionally stable sheet is opaque and said dyeable polymeric layer is positioned intermediate said support layer and the selectively sensitized silver halide emulsion layer next adjacent thereto.
 39. A process as defined in claim 37 wherein said dimensionally stable support layer is opaque; said dimensionally stable sheet is transparent and said selectively sensitized silver halide emulsion layer is positioned intermediate said support layer and said dyeable polymeric layer.
 40. In a process of forming transfer images in color, as defined in claim 37, which comprises, in combination, the steps of: a. exposing a photographic film unit which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members and which includes, in combination: a photosensitive laminate containing, as essential layers, a blue-sensitive silver halide emulsion layer having associated therewith a yellow dye, a green-sensitive silver halide emulsion layer having associated therewith a magenta dye, a red-sensitive silver halide emulsion layer having associated therewith a cyan dye, each of said cyan, magenta and yellow dyes being silver halide developing agent and being soluble and diffusible, in alkali, at a first pH, as a function of the exposure of its associated silver halide emulsion layer, an alkaline solution permeable polymeric layer dyeable by each of said dyes, a dimensionally stable alkaline solution impermeable support layer, and an alkaline solution permeable polymeric acid layer containing sufficient acidifying groups to effect reduction of a processing solution having said first pH to a second pH at which said dyes are substantially insoluble and nondiffusible positioned intermediate said support layer and the next adjacent essential layers; a dimensionally stable sheet fixedly positioned superposed on the surface of the laminate opposite said support layer; and a rupturable container retaining an aqueous alkaline processing composition having said first pH fixedly positioned and extending transverse a leading edge of said laminate to effect unidirectional discharge of the container''s contents on the surface of said laminate intermediate said transparent sheet and said laminate upon application of compressive force to said container; b. applying compressive force to said rupturable container to effect unidirectional discharge of the container''s alkaline solution intermediate said transparent sheet and said laminate; c. effecting thereby development of the latent image contained in each of said silver halide emulsions; d. immobilizing said yellow, magenta and cyan dye, as a result of deveLopment of their respective associated silver halide emulsions; e. forming thereby an imagewise distribution of mobile yellow, magenta and cyan dye, as a function of the point-to-point degree of exposure of their respective associated silver halide emulsions; f. transferring, by diffusion, at least a portion of each of said imagewise distributions of mobile dye to said alkaline solution permeable polymeric layer dyeable by said dyes to provide thereto a multicolor dye image; g. transferring, by diffusion, subsequent to substantial transfer image formation, a sufficient portion of the ions of said aqueous alkaline solution to said alkaline solution permeable polymeric acid layer to thereby reduce the alkalinity of said solution to said second pH; and h. maintaining the laminate intact subsequent to processing; the improvement which comprises a processing solution solubilized dye permeable layer which includes light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible light-reflecting agent in a concentration sufficient to mask said dyes associated with said photosensitive silver halide emulsion layers subsequent to processing positioned intermediate said dyeable polymeric layer and the photosensitive silver halide layer next adjacent and effecting thereby interaction between said first and said second ionic species upon contact of said light-reflecting agent precursor layer with said processing composition thereby providing said substantially white, inorganic visible light-reflecting agent intermediate said dyeable polymeric layer and the photosensitive silver halide emulsion layer next adjacent.
 41. A process as defined in claim 37 wherein said first pH is above 9 and said second pH is below
 9. 42. A process as defined in claim 37 wherein said processing solution includes an opacifying agent.
 43. A process as defined in claim 37 wherein said visible light-reflecting agent precursor comprises barium sulfide and said processing solution includes zinc sulfate. 